What is a Microprocessor?

Microprocessor?

• Digital IC built into a square of silicon.
• “Brain” of a computer
• Also called as CPU - Incorporates functions of CPU on a single chip
• Programmable device that accepts digital data as input
• Example of sequential digital logic, as it has internal memory
• Perform arithmetic operations, transfer data, make decisions

What does a Microprocessor have? 

• Contain millions of transistors connected by extremely fine wires of aluminum or copper. 
• Consists of a control unit and an arithmetic and logical unit (ALU)
• Every microprocessor has a fixed set of instruction for its operation
• Has address bus, or pathway, along which addresses for storing data travel.
• Has data bus, or pathway, along which data is sent to and retrieved from memory.
• Read (RD) and write (WR) lines (connections) that instruct memory. 
• A clock line that determines when data is sent
• Arithmetic Logic Unit
• Intruction Decoder
• Registers

How will you choose a Microprocessor?

Microprocessors are defined by the following three characteristics 

• Clock speed. In MHz, of how many pulses per second are generated by an oscillator within the chip.
• Bandwidth (of the data bus). The number of bits of information (1s or 0s) that can be processed at a time.
• Instruction set. The complexity of the instructions the microprocessor is capable of performing.

How does a Microprocessor work?

• Fetch -  Microprocessor first fetches the instruction from the address stored in the Program Counter (PC).
• Decode  -  Fetched instruction is decoded so that it can be interpreted by the microprocessor.
• Execute -  Once decoded, the instruction can then be executed and the PC incremented so that it contains the address of the next instruction

History of Microprocessor


1.  Intel 4004 - 1971 - 4bit microprocessor used in calculators
2.  Intel 8008 - 1972 - 8bit microprocessor
3.  Motorola 6800- 1974 - 8bit microprocessor
4.  Intel 8080 - 1975 - 8bit microprocessor
5.  Zilog Z80 - 1976 - 8bit microprocessor
6.  Intel 8085 - 1977 - 8bit microprocessor
7.  Intel 8086 - 1978 - 16bit microprocessor
8.  Intel 8088 - 1979 - 16bit microprocessor